Mr. Biden emerged from the meeting offering some professional respect for Mr. Putin as an adversary. For his part, Mr. Putin said, “There has been no hostility.” At one point, Mr. Biden asked the Russian leader how he would feel if Russia’s gas pipelines were attacked from afar — a comment that some interpreted as a threat to the Russian leader.
For a few months, ransomware gangs were in retreat, and not long ago the Russian police, based on information from the United States, arrested a group of what they described as criminal hackers. But now there is fear that the ransomware gangs could be unleashed, as could hacking groups like Sandworm, which has been linked to the G.R.U., the Russian military intelligence unit. Sandworm is believed to be responsible for hacks of the Ukrainian power grid and multiple targets in the United States.
For more than a month, the director of the Cybersecurity and Infrastructure Security Agency, Jen Easterly, has been issuing a series of what she calls “Shields Up” tweets and making public appearances to encourage more resiliency in the nation’s privately-controlled computer networks.
Together with the British, the F.B.I. and the National Security Agency, Ms. Easterly’s agency recently revealed the technical details for a new strain of malware it has seen. It turns out that it was derived from one of the most destructive attacks ever conducted, which was aimed at Ukraine in 2017.
For America’s largest banks and utilities, this was old news: They have studied Russian attacks on Ukraine and other nations for years. But for companies that have invested far less in fending off attack, resiliency takes time to build up, so no one thinks that last-minute warnings to lock down vulnerable systems, while helpful, are enough.
For years, the U.S. government has warned that Russia has inserted malicious code in American networks, including the power grid, that could be triggered at a later date. (The United States has done the same in Russia.) But so far, Russia has been hesitant to unleash that “sleeper code.” The U.S.-led sanctions may tempt Russian leaders to unleash it, some speculate.
Then there is the problem of “digital fallout,” the phrase Ciaran Martin, the former chief of Britain’s National Cyber Security Center, used to describe attacks on Ukraine that “ripple outward to disrupt businesses and government around the world.”
